Proteomics of sea bass skin-scales exposed to the emerging pollutant fluoxetine compared to estradiol.

Teleost fish skin-scales are essential for protection and homeostasis and the largest tissue in direct contact with the environment, but their potential as early indicators of pollutant exposure are hampered by limited knowledge about this model. This study evaluated multi-level impacts of in vivo exposure of European sea bass to fluoxetine (FLX, a selective serotonin-reuptake inhibitor and an emerging pollutant) and 17ß-estradiol (E2, a natural hormone and representative of diverse estrogenic endocrine-disrupting pollutants). Exposed fish had significantly increased circulating levels of FLX and its active metabolite nor-FLX that, in contrast to E2, did not have estrogenic effects on most fish plasma and scale indicators. Quantitative proteomics using SWATH-MS identified 985 proteins in the scale total proteome. 213 proteins were significantly modified 5 days after exposure to E2 or FLX and 31 were common to both treatments and responded in the same way. Common biological processes significantly affected by both treatments were protein turnover and cytoskeleton reorganization. E2 specifically up-regulated proteins related to protein production and degradation and down-regulated the cytoskeleton/extracellular matrix and innate immune proteins. FLX caused both up- and down-regulation of protein synthesis and energy metabolism. Multiple estrogen and serotonin receptor and transporter transcripts were altered in sea bass scales after E2 and/or FLX exposure, revealing complex disruptive effects in estrogen/serotonin responsiveness, which may account for the partially overlapping effects of E2 and FLX on the proteome. A large number (103) of FLX-specifically regulated proteins indicated numerous actions independent of estrogen signalling. This study provides the first quantitative proteome of the fish skin-scale barrier, elucidates routes of action and biochemical and molecular signatures of E2 or FLX-exposure and identifies potential physiological consequences and candidate biomarkers of pollutant exposure, for monitoring and risk assessment.

Exogenous 17ß-oestradiol (E2) modifies thymus growth and regionalization in European sea bass Dicentrarchus labrax.

The effect of 17ß-oestradiol (E2) on the growth of the thymus and its regionalization into cortex and medulla was investigated in juvenile European sea bass Dicentrarchus labrax as they find themselves close to sources of oestrogenic pollution whilst residing in their estuarine nursery areas. While the exposure to 2, 20 and 200 ng l(-1) in 60 days post-hatch (dph) fish tended to cause a non-monotonous dose-response curve with a significant difference of the cortex size between lowest and highest exposures, the exposure to 20 ng l(-1) E2 from 90 dph onwards resulted in a distinct enlargement of the cortex. It is probable that the alteration of the cortex size also affects the T-cell differentiation and proliferation.

C3A binds to the seven transmembrane anaphylatoxin receptor expressed by epithelial cells and triggers the production of IL-8.

The complement (C) plays an important role in many acute inflammatory processes. C3a is an inflammatory polypeptide named anaphylatoxin, generated during C activation and which acts through a specific receptor C3aR. In this study, we demonstrated that the epithelial cell line ECV 304 constitutively expressed C3aR (by flow cytometry and immunofluorescence) and that binding of purified C3a to epithelial cells resulted in a time- and dose-dependent upregulation of interleukin-8 (IL-8). Pre-treatment of ECV 304 with pertussis toxin inhibited IL-8 response induced by C3a, indicating that the action of C3a was mediated by a G protein coupled pathway.

Complement and its implications in cardiac ischemia/reperfusion: strategies to inhibit complement.

Although reperfusion of the ischemic myocardium is an absolute necessity to salvage tissue from eventual death, it is also associated with pathologic changes that represent either an acceleration of processes initiated during ischemia or new pathophysiological changes that were initiated after reperfusion. This so-called "reperfusion injury" is accompanied by a marked inflammatory reaction, which contributes to tissue injury. In addition to the well known role of oxygen free radicals and white blood cells, activation of the complement system probably represents one of the major contributors of the inflammatory reaction upon reperfusion. The complement may be activated through three different pathways: the classical, the alternative, and the lectin pathway. During reperfusion, complement may be activated by exposure to intracellular components such as mitochondrial membranes or intermediate filaments. Two elements of the activated complement contribute directly or indirectly to damages: anaphylatoxins (C3a and C5a) and the membrane attack complex (MAC). C5a, the most potent chemotactic anaphylatoxin, may attract neutrophils to the site of inflammation, leading to superoxide production, while MAC is deposited over endothelial cells and smooth vessel cells, leading to cell injury. Experimental evidence suggests that tissue salvage may be achieved by inhibition of the complement pathway. As the complement is composed of a cascade of proteins, it provides numerous sites for pharmacological interventions during acute myocardial infarction. Although various strategies aimed at modulating the complement system have been tested, the ideal approach probably consists of maintaining the activity of C3 (a central protein of the complement cascade) and inhibiting the later events implicated in ischemia/reperfusion and also in targeting inhibition in a tissue-specific manner.